Associations between program outcomes and adherence to Social Cognitive Theory tasks: process evaluation of the SHED-IT community weight loss trial for men

BACKGROUND Despite rising international rates of obesity, men remain reluctant to participate in weight loss research. There is a lack of evidence to guide the development of effective weight loss interventions that engage men. The objective of this study was to provide a comprehensive process evaluation of the SHED-IT (Self-Help, Exercise and Diet using Information Technology) weight loss program for men, as delivered in the SHED-IT community weight loss trial, and to identify key components associated with success. METHODS In an assessor-blinded randomised controlled trial, 159 overweight and obese men (BMI 25.0-40.0 kg/m2) were randomised to one of two gender-tailored weight loss interventions with no face-to-face contact, or a control group. The interventions were informed by Bandura's Social Cognitive Theory (SCT) with men encouraged to complete a Support Book containing SCT-based tasks including goal setting, reward setting, creation of social support strategies and self-monitoring of: i) weight, ii) physical activity, and iii) diet. At post-test, compliance with SCT tasks was examined and men also completed a process evaluation questionnaire. RESULTS Both SHED-IT intervention groups demonstrated greater weight loss during the intervention compared to the control, with no difference between intervention groups. Most men engaged with the SCT tasks although compliance declined over time and utilisation of social support networks and reward selection was poor. In a multiple regression model, the number of goals set (β [95% CI] = -0.3 [-0.6, -0.1], p = 0.01) and the number of weight records documented (β [95% CI] = -0.2 [-0.4, -0.0], p = 0.03) independently predicted weight loss. The process evaluation indicated that men found the programs to be supportive, enjoyable and beneficial. CONCLUSIONS This process evaluation provides valuable information to inform the development of obesity treatment strategies that engage men. Future studies with men should include a strong focus on self-monitoring and goal setting to enhance behaviour change and improve treatment effects. TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry ACTRN12610000699066.